Understanding your result
All outputs represent the same pressure difference or absolute pressure as the input. A negative gauge value stays negative; the tool does not add atmospheric pressure or establish whether a reading is physically valid for an application.
For a separate temperature measurement, use the Temperature Converter .
The formula
Each unit is a multiplicative scale relative to the pascal. The psi factor uses pounds-force per square inch, not pounds of mass per square inch. Display rounding occurs after conversion, with six fractional digits where practical.
Worked example
An input of 1 bar equals 100,000 Pa, 100 kPa, 0.1 MPa, and approximately 14.503774 psi. One standard atmosphere instead equals 101,325 Pa and 760 Torr; it is not exactly one bar.
How to use this calculator
- Enter the numerical pressure, including a minus sign only if appropriate to its reference.
- Select the unit stated on the instrument or specification.
- Read the required equivalent and retain the original gauge or absolute label.
Gauge and absolute pressure are different references
A gauge reading measures pressure relative to a reference, commonly the surrounding atmosphere. Absolute pressure uses a vacuum reference. Changing psi to bar does not convert one reference into the other. Adding a fixed atmospheric value would require an explicit assumption, so this converter does not do so automatically.
Use the unit written on the instrument
Standard atmosphere and bar are close but unequal. Torr is defined here as one seven-hundred-and-sixtieth of a standard atmosphere; it should not be silently substituted for every mercury-column convention. Water-column units depend on a stated convention and are not included. Preserve enough input precision for the task, and avoid interpreting extra displayed digits as improved instrument accuracy.
Assumptions & limitations
What this calculation assumes
- The entered unit and pressure reference have been correctly identified.
What to keep in mind
- No gauge-to-absolute conversion, altitude correction, or equipment pressure rating assessment.
Common questions
Can I enter a vacuum-gauge reading?
Yes, as a signed relative pressure, provided the unit is supported. The outputs retain that relative reference.
Why are Pa and kPa so different numerically?
The prefix kilo means one thousand. A pressure of 100 kPa is the same quantity as 100,000 Pa.